<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Test WEB</title>
    <style>
        html,body,.content{
            height: 100%;
            width: 100%;
            display: flex;
            justify-content: center;
            align-items: center;
        }
    </style>
</head>
<body>
<div class="content">
    <span>test web</span>
</div>
</body>
</html>